btrfs: compression: inline get_workspace

Majority of the callbacks is trivial, we don't gain anything by the
indirection, so replace them by a switch function.

ZLIB needs to adjust level in the callback and ZSTD workspace management
is complex, the rest is call to the helper.
Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/compression.c

@@ -50,7 +50,6 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 		size_t destlen);
 struct list_head *lzo_alloc_workspace(unsigned int level);
 void lzo_free_workspace(struct list_head *ws);
-struct list_head *lzo_get_workspace(unsigned int level);
 void lzo_put_workspace(struct list_head *ws);
 
 int zstd_compress_pages(struct list_head *ws, struct address_space *mapping,
@@ -874,11 +873,6 @@ struct heuristic_ws {
 
 static struct workspace_manager heuristic_wsm;
 
-static struct list_head *heuristic_get_workspace(unsigned int level)
-{
-	return btrfs_get_workspace(&heuristic_wsm, level);
-}
-
 static void heuristic_put_workspace(struct list_head *ws)
 {
 	btrfs_put_workspace(&heuristic_wsm, ws);
@@ -925,7 +919,6 @@ static struct list_head *alloc_heuristic_ws(unsigned int level)
 
 const struct btrfs_compress_op btrfs_heuristic_compress = {
 	.workspace_manager = &heuristic_wsm,
-	.get_workspace = heuristic_get_workspace,
 	.put_workspace = heuristic_put_workspace,
 	.alloc_workspace = alloc_heuristic_ws,
 	.free_workspace = free_heuristic_ws,
@@ -1067,7 +1060,21 @@ struct list_head *btrfs_get_workspace(struct workspace_manager *wsm,
 
 static struct list_head *get_workspace(int type, int level)
 {
-	return btrfs_compress_op[type]->get_workspace(level);
+	struct workspace_manager *wsm;
+
+	wsm = btrfs_compress_op[type]->workspace_manager;
+	switch (type) {
+	case BTRFS_COMPRESS_NONE: return btrfs_get_workspace(wsm, level);
+	case BTRFS_COMPRESS_ZLIB: return zlib_get_workspace(level);
+	case BTRFS_COMPRESS_LZO:  return btrfs_get_workspace(wsm, level);
+	case BTRFS_COMPRESS_ZSTD: return zstd_get_workspace(level);
+	default:
+		/*
+		 * This can't happen, the type is validated several times
+		 * before we get here.
+		 */
+		BUG();
+	}
 }
 
 /*

fs/btrfs/compression.h

@@ -125,8 +125,6 @@ struct list_head *btrfs_get_workspace(struct workspace_manager *wsm,
 void btrfs_put_workspace(struct workspace_manager *wsm, struct list_head *ws);
 
 struct btrfs_compress_op {
-	struct list_head *(*get_workspace)(unsigned int level);
-
 	void (*put_workspace)(struct list_head *ws);
 
 	struct list_head *(*alloc_workspace)(unsigned int level);

fs/btrfs/lzo.c

@@ -63,11 +63,6 @@ struct workspace {
 
 static struct workspace_manager wsm;
 
-struct list_head *lzo_get_workspace(unsigned int level)
-{
-	return btrfs_get_workspace(&wsm, level);
-}
-
 void lzo_put_workspace(struct list_head *ws)
 {
 	btrfs_put_workspace(&wsm, ws);
@@ -494,7 +489,6 @@ int lzo_decompress(struct list_head *ws, unsigned char *data_in,
 
 const struct btrfs_compress_op btrfs_lzo_compress = {
 	.workspace_manager	= &wsm,
-	.get_workspace		= lzo_get_workspace,
 	.put_workspace		= lzo_put_workspace,
 	.alloc_workspace	= lzo_alloc_workspace,
 	.free_workspace		= lzo_free_workspace,

fs/btrfs/zlib.c

@@ -405,7 +405,6 @@ int zlib_decompress(struct list_head *ws, unsigned char *data_in,
 
 const struct btrfs_compress_op btrfs_zlib_compress = {
 	.workspace_manager	= &wsm,
-	.get_workspace		= zlib_get_workspace,
 	.put_workspace		= zlib_put_workspace,
 	.alloc_workspace	= zlib_alloc_workspace,
 	.free_workspace		= zlib_free_workspace,

fs/btrfs/zstd.c

@@ -708,7 +708,6 @@ int zstd_decompress(struct list_head *ws, unsigned char *data_in,
 const struct btrfs_compress_op btrfs_zstd_compress = {
 	/* ZSTD uses own workspace manager */
 	.workspace_manager = NULL,
-	.get_workspace = zstd_get_workspace,
 	.put_workspace = zstd_put_workspace,
 	.alloc_workspace = zstd_alloc_workspace,
 	.free_workspace = zstd_free_workspace,